Photoelectric thermionic cell



oct. 13, 1936.

E. HOPKINS PHOTOELECTRIC THERHIONIC CELL Original Filed Jan. 26, ,1922

J5 Inventor:

Patented Oct. 13, 1936 UNITED STATES PATENT OFFICE Application January 26, 1922, Serial No. 531,990 Renewed January 4, 1934 58 Claims. (Cl. 179-171) In carrying out my invention I find it desirable to employ the following apparatus, methods, processes and manufactures, but it is to be understood that in carrying out the objects of my invention, less than all of the different methods, means, mechanisms, processes and manufactures herein described may be employed, or other methods, means, mechanisms,process and manufactures similar may be substituted, and while the preferred methods and forms embodying my invention are shown, it is to be understood that many of the structural details may be varied and many changes in details resorted to without departing from the scope and spirit of my invention, nor do I limit myself to the particular methods, means, devices and processes shown, although I believe them especially suited to the ends to be attained by my invention.

In the accompanying drawing, illustrating a form of the invention, and forming a part hereof, the same reference letters and numerals indicate the same or corresponding parts.

Fig. 1 is a transverse cross section of a photoelectric cell suitable for recording voice frequencies, taken on line J of Fig. 2.

Fig. 2 is a longitudinal cross section on line K of Fig. 1.

Fig. 3 is a detailed elevation of the photoelectric element and its supports.

Fig. 4 is a plan of the grid.

Fig. 5 is a side elevation of the grid.

Fig. 6 is a longitudinal cross section of a variant form of photoelectric cell.

Figs. 7, 8 and 9 are diagrams of electrical connections of the photoelectric cells.

Figs. 1 to 9 illustrate special forms of photoelectric cells and diagrams of connections, within my invention.

The main novelty of this photoelectric cell lies in the fact that it is a4 combined photoelectric cell and audion in which the photoelectrlc element is electrically heated and is electrically independent, free or floating as respects the other circuits.

An evacuated envelope of glass or fused quartz I, with base 3| cemented on by cement 32 contains a foundation tube or cylinder preferably of glass or quartz 2 bearing a helical channel in many turns in which is supported or wrapped an electrical conductor I8 in the nature of a filament with terminals 29, 30, the latter descending through an insulating aperture in the side wall of the foundation. 'I'his filament is covered with any photoelectrical substance, that is one that emits what are presumably negative electrons when exposed to light, among such substances being strontium, barium, radium bromide, sodium and their oxides and salts and the like. The object of heating the photoelectric helix electrically is to, bring it up to about a red 5 glow so that it will be more active in eect when exposed to the light than if left cold, although it will function if left cold, in a very limited degree.

In the center of the bulb I is an insulating stem 3 which carries at the top a metallic plate 4 having a metallic stem 5 supporting a hemispherical cup 6, such plate, stem and cup being integral physically and electrically and connected to the terminal I at the bottom of the bulb. It forms the plate or anode element for both the photoelectric cell action and the audion action, a novel feature of this invention. Encircling the stem but independent therefrom is filament 8, adapted to be heated to incandescence, and having terminals 9 and I0. Encircling the filament 8 is the grid II, supported on stems I2, I3, I4, stem I2 leading to terminal I5. This filament, 8, with grid II and plate! constitute an audion. At the base of the cylinder 2 is an electrical conductor or cathode Il having terminals I8, I9 and supported on insulating standard 20. The cathode I'I may be covered with photoelectric material, and it, with anode plate 6 would then constitute a photoelectric cell as ordinarily used, the cathode and anode being maintained at a dierence of potential and current flowing when light strikes the cathode, due to emanations caused by the light, presumably negative electrons released by the photoelectric substance.

It is not necessary, however, in this invention, for cathode II to be covered with photoelectric material, as filament I 6 is so covered and offers a large surface for the impinging of the light, which strikes not only normally or head-on but at various glancing angles. 'I'he heating of I6 increases the eiect of the light very markedly. When light strikes filament I 6 it releases a field of electrons through which current from cathode I'I passes to anode plate 8. 'I'his photoelec- 45 tric cell with an independent photoelectric element heated is new in the art. The element may' consist of a tube instead of a helix of wire, such tube having terminals at top and bottom adapting it to `be heated. The plate 6 may be so at- 50 tached to the top of the cylinder as to be airtight if desired. The photoelectric part and the audion part may be in separately evacuated chambers if desired.

Plate 4, 5, 6 is a common anode for both photolocation with respect to plate 4 is such that the device may be employed at different potentials :ai different purposes. as is well understood in art.

Fig. 6 indicates a variant of the cell, the plateanode 2| being at the base with terminal 22, the photoelectric element 24 being wound on cone 24 with terminals 2B, 2l and the cathode 2s being umbrella shaped with terminal 2l. This form may be hung at an elevation and-receive light cast upward from below from various angles.

For some uses all the elements of the cell may not be employed. Fig. 'I is a diagram of connections oi a simple electrical organization. Independent photoelectric element is heated licy battery 34. In the presence of light it gives o!! negative electrons indicated by dots Il. Filament l5 supplied by illament battery 48 gives oi! negative electrons indicated by dots in arrow heads 40 and a current oi' negative electricity flows to the plate l1, then tomain battery 38 and performs work at W 4I. The emanations from 33 due to the light rays vary with the light and thus provide an improved path, changing from instant to instant, for the current from lament to plate, which thus increases with the intensity of the light. A

In Fig. 8 is shown an electrical organization based on a modiilcation ot cell I. Light shining on independent photoelectric element heated by battery 34 produces emanations 39 which enable negative electrons 40 from iilament 3B heated by battery 36 to ilow more readily to plate 31. These negative. electrons 40 reach battery 38 and the battery performs work at W 4|. In parallel, however, is the grid circuit with grid 42 in the audion part of the cell. Grid battery 43 is to adjust the potential of the grid and in some uses may be dispensed with. When the light increases in intensity and enables battery 38 to perform more work by the improved path 35-40-31 this also affects the grid potential and opens up path 3544-42-31, permitting the battery lato perform still more work. In order to put this arr-angement into eiect holes would have to be made in the wall of 2 or else I1 be utilized as a part of filament 8.

It is to be noted that in indicating the direcy tion of the current'ilow the direction of flow of negative electrons is followed, they ilowing into the plus side of the battery, rather than the older method which indicated electric current proceeding from the plus side.

In Fig. 9v is shown arr electrical organization for utilizing. the properties of cell i. Independent photoelectric element 33 heated by battery 34 producesr emanations 39 which enable negative electrons 40, indicated by arrow heads and dots, from filament 41 heated by battery 48 to ilow more readily to plate 31. However, it is not essential that 41 be a illament, as it may simply be cathode l1 not heated, and maintained at a difference of potential with plate 31 (equivalent to anode-plate 6) although it is withln'the invention for i1 to be rendered hot or incandescent by a battery. The work done by battery at 4i W increases thus according to the intensity of the light. The grid battery 43 is for purposes of adjusting the potential of the grid and in certain cases may be dispensed with. The potential and even the sign of the grid 42 may be changed by the increase ot light. In addition plate and grid circuits are regeneratively coupled at 4l.

4l, still further improving the path 3U, 44, v42, l1

whenever the path 41, 40, Il, 31 is improved by increases in light intensity. 'Ihus a very appre- ,ciable variation in work may be developed at W 4i upon slight variations in a light source shining on 3l.

The electrical organizations given are merely illustrations'of the uses to which the cell may be put and many others may be detlned. There are in the audion and photoelectricl arts a great number of electrical organizations or circuits, including forms of Wheatstone bridge, positive and negative resistances, trap actions and the like which it would be impossible to describe here, but any of which may be utilized in connection with this cell under suitable circumstances. The batteries and resistances may be made variable or adjustable when desired. 'I'he base is adapted to be screwed down on a socket containing concentric rings, cut across if desired at selected points, to make contacts with the terminals.

What I claim is:

l. A photoelectric cell comprising al cathode,

an anode and an independent lphotoelectric ele-V heated, a photoelectric element plastered on such conductor and adapted to be heated by the heating of such conductor by electrical resistance,

and means'for applying current therefor, and a common anode for the audion and the photoelectric element, all contained in an evacuated envelope.

3. A photoelectric audion cell comprising an evacuated envelope containing live elements; an anode in the form of a transverse plate surmounted by a rod carrying additional anode material oi hemispherical contour with the rod as an internal axis, such anode supported on a central longitudinal stem; an audion filament encircling the stem, an audion grid encircling the illament; a photoelectrically active substance in numerous helical turns adapted to be heated by electrical means independent of the other elements, supported on a tubular member of insulating material encircling the grid, and a cathode encircling the tubular support near its base; with external electrical terminals for such elements, one each for the anode and grid, and two each for the filament, cathode and photoelectric element, such photoelectric-audion cell having an external base for mounting.

4. A photoelectric cell containing a photoelectric element in a plurality of helical turns carried on a cylindrical member placed axially in the cell, whereby such photoelectric element may receive light rays from all angles of all planes to which the axis oi such helix is normal.

5. A photoelectric cell in combination with an audion cell in the same evacuated envelope, comprising an audion grid, a common cathode for the photoelectric action and the audion action,

and a common anode for the photoelectric action and the audion action.

6. In a photoelectric-audion cell separate chambers separately evacuated, for the photoelectric elements and -i'or the audion elements, with an anode electrically common to both.

'7. An organization oi electrical circuits and elements for photoelectric use including an audion and a photoelectric element, such photoelectric element comprising a cold `photoelectric cathode in a cathode to anode primary work circuit, whose electron path is adapted to be altered by changes in rays of light striking the photoelectric element; a illament heating circuit; a grid circuit; a lament-grid-anode work circuit in parallel with the cold cathode-anode work circuit, and a regenerative coupling between the grid circuit and the illament-grid-anode work circuit.

8. An organization of electric circuits and elements for photoelectric use comprising a primary and a secondary work circuit, the primary circuit comprising a iilament heating circuit and a hot iilament to anode work circuit whose electron path is subjected to be iniiuenced by an independent photoelectric element; the secondary work circuit including a illament and heating circuit and a hot lament to grid to anode work circuit in parallel with the primary work circuit,

a grid circuit, an independent photoelectric element with an independent heating circuit adapted to influence or alter the electron path oi the primary work circuit upon the incidence of rays oi light upon the independent photoelectric element, and regenerative connection between the grid circuit and the work circuits.

9. A photoelectric cell having a cathode, an anode, and an independent element comprising photoelectric substance mounted on an electric conductor insulated from the rest oi the system. such conductor adapted to be heated by resistance to an electric current passed through it, means for so passing such current through it, whereby to increase the photoelectric effect by reason of such heating of such conductor and photoelectric substance mounted thereon.

10. In combination, a photoelectric cell and an audion cell, said audion comprising a cathode, a grid and an anode; said photoelectric cell comprising a cathode, an anode and with said anode conductively connected to said audion anode, and a supplementary electrode element operatively associated with said photoelectric cell cathode and anode, comprising a photoelectric substance and means adapted to heat the photoelectric substance of said supplementary photoelectric electrode element.

11. In combination, a photoelectric cell and an audion cell, said audion comprising a cathode, a grid and an anode; said photoelectric cell comprising a cathode, an anode and with said anode conductively connected to said audion anode, including a supplementary electrode element operatively associated with said photoelectric cell cathode and anode, comprising a photoelectric substance and means adapted to heat the photoelectric substance of said supplementary photoelectric electrode element when said heating means comprises an electrical conductor in a closed energizable circuit, said circuit and means adapted to energize it, and said conductor of such form and resistivity as to beadapted to be heated upon closing of said circuit.

12. In combination, a photoelectric cell and an audion cell, said audion comprising a cathode, a

grid and an anode: said photoelectric cell comprising a cathode, an anode and means conductively connecting said anode to said audion anode; a supplementary electrode element operatively associated with said photoelectric cell cathode and anode, comprising a photoelectricsubstance, and means adapted to heat the photoelectric substance oi said supplementary photoelectric electrode element, said heating means comprising an electrical conductor in a closed energizable circuit. said circuit and means adapted to energize it, said conductor of such form and resistivity as to be adapted to be heated upon the closing of said circuit, and said conductor electrically insulated from the remainder of the system.

13. In combination, a photoelectric cell and an audion cell, said audion cell comprising a cathode, a grid and an anode, said photoelectric cell comprising a cathode and an anode, said anode conductively connected to said audion anode, and a supplementary electrode element operatively associated with said photoelectric cathode and anode, comprising a photoelectric substance; and supported and electrically connected with said photoelectric substance, an electrical conductor in a closed energized circuit, said circuit and means adapted to energize said circuit, and said conductor oi' such form and resistivity as to be heated on the closing of said circuit.

14. The matter of claim 13 when the elements, .except said energizing means and connections thereto are contained in an evacuated envelope.

l5. The matter of claim 13 when said electrical conductor of the closed energized circuit is electrically insulated from the remainder of the system in the envelope.

16. 'I'he matter of claim 13 when said electrical conductor of the closed energized circuit is electrically insulated from said supplementary electrodes photoelectric substance.

17. The matter of claim 13 when the photoelectric cell and supplementary electrode are contained Within a second evacuated envelope within the outer evacuated envelope.

18. The matter of claim 13 comprising a main outer evacuated envelope of fused quartz and within said envelope an inner evacuated envelope of iused quartz, adapted to be separately evacuated, said inner envelope adapted to contain said photoelectric anode, cathode and supplementary electrode.

19. In a combined audion-photoelectric cell having a cathode and grid for the audion portion, and a primary cathode for the photoelectric portion and an anode so positioned as to be electrically and physically integral and adapted to function as a common anode for both portions, a supplementary cathode for the photoelectric portion positioned between said anode and said primary photoelectric cathode, comprising a photoelectric substance and adapted, upon being struck by light to alter the conductivity of the electronic path between said primary cathode and said anode.

20. In a photoelectric cell combined with an audion cell, said photoelectric element comprising a primary cathode. a support therefor, a secondary cathode electrode, a support therefor, and an anode and a support therefor; said audion element comprising a cathode, a support therefor, a grid, a support therefor and an anode electrically integral with said photoelectric anode adapted to be supported by the anode support of said photoelectric element's anode, said supplementary electrode support having an internally disposed cavity in which said audion grid and its support and said audion cathode and its support are adapted to be contained and positioned, and said supplementary electrode having' an external surface bearing photoelectric substance and adapted to receive rays oi light from all external directions except as obscured by said primary cathode, anode and the several supports of the various elements. Y

21. 'I'he matter of claim 20'in which the supplementary photoelectric electrode is in form a hollow cylinder, having on its external surface photoelectric substance, and is so positioned and supported as to be adapted to receive rays of light from all angles of all planes normal tothe axis of said cylinder. l

22. The matter of claim 4 whenu the photoelectric element is mounted on a conical pyramid placed axially in the cell, whereby such element may receive rays of light from all angles to which it may be exposed.

23. The matter of claim 4 when said photoelectric element in a plurality of turns is a supplementary electrode of the photlectric element of a combined audion and photoelectric cell of the class described.

24. An organization of electrical elements and circuits for photoelectric purposes, comprising a primary work circuit, having cathode and anode and a space gap therebetween, an independent photoelectric element so positioned 'as to alter the conductivity of said cathode-to-anode work circuit gap upon the incidence of light striking said photoelectric element, a supplementary work circuit from said cathode through a'grid to said anode, and a grid circuit in said supplementary work circuit. 25. The matter of claim 24 when the primary work circuit cathode is supplied with a heating circuit, whereby to heat said cathode.

26. The matter of claim 24 when said photoelectric element is provided with an independent heating circuit, independent of said work circuit, and adapted to supplyv electrons to said photoelectric element upon the withdrawal of electrons consequent upon said incidence of light-upon said photoelectric element.

27. The matter of claim 24 when the primary work circuit cathode is supplied with a heating circuit, whereby to heat said cathode and when said photoelectric element is provided with an independent heating circuit, independent of Asaid work circuit, and adapted to supply electrons to said photoelectric element upon the withdrawal of electrons consequent upon said lincidence of light. upon said photoelectric element.

28. The matter of claim 24 whenv said grid circuit is provided with critical biasing means adapted upon incidence of light on said photoelectric element to change sign or reverse direction of current of said work circuits.

29. The matter of claim 24 when the primary work circuit cathode is supplied witha heating circuit, whereby to heat said cathode and when said grid circuit is provided with critical biasing means adapted upon incidence of light on said photoelectric element to change sign or reverse direction of current of said work circuits.

30. The matter of claim 24 when said photoelectric element is provided with an independent heating circuit, independent of said work circuit, and adapted to supply electrons to said photoelectric element upon the withdrawal oi electrons consequent upon said incidence of light upon said photoelectric element and when said grid circuit is provided with critical biasing means adapted upon incidence oflight on saidphotoelectric element to change sign or reverse direction o! current oi' said work circuits.

31. The matter of claim 24 when the primary work circuit cathode is supplied with a heating circuit, whereby to heat said cathode and when said photoelectric element is provided with an independent heating circuit, independent of said work circuit, and adapted to supply electrons to said photoelectric element upon the withdrawal of electrons consequent upon saidl incidence of light upon said photoelectric element and when said grid circuit is provided with critical biasing means adapted upon incidence of light on said photoelectric element to change sign or reverse direction of current of said work circuits.

32. An organization of electrical elements and circuits comprising a primary work circuit having a cathode and an anode, with a space gap therebetween, an independent photoelectric element, so positioned as to alter the conductivity of said cathode-to-anode space gap of said primary work circuit, upon incidence oi' rays of light upon said photoelectric element, a secondary work circuit oi' the audion type, having a cathode y adapted to be heated, an anode, a cathode-toanode gap therebetween, a grid positioned in said gap, with a grid circuit in conjunction with said secondary work circuit, 'said primary and secondary anodes electrically identical, and means adapted to regeneratively couplesaid grid and said work circuits.

33. The matter of claim 32 when provided with a primary work circuit cathode-heating circuit adapted to heat the said cathode on being energized, and means to energize said heating circuit.

34. The matter of claim 32 when the photoelectric element is provided with a heating circuit, independent of said work circuits, said circuit adapted to supply electrons to said photoelectric element upon the withdrawal of electrons therefrom consequent upon the incidence of light rays on said photoelectric element.

35. The matter of claim 32 when provided with a primary work circuit cathode-heating circuit adapted to heat the said cathode on being energized and means to energize said heating circuit, and when the photoelectric element is provided with a heating circuit, independent of said work circuits, said circuit adapted to supply electrons to said photoelectric element upon the withdrawal of electrons therefrom consequent upon the incidence of light rays on said photoelectric element.

36. The matter oi' claim 32 when said grid circuit is provided with critical biasing means adapted to change sign or direction of current of work circuits on the incidence of a selected threshold of light on'the photoelectric element.

37. The matter of claim 32 when provided with a primary work circuit cathode-heating circuit adapted to heat the said cathode on being energized, land means to energize said heatsupply electrons to said photoelectric element upon the withdrawal of electrons therefrom consequent upon the incidence of light rays on said photoelectric element, and when said grid circuit is provided with critical biasing means adapted to change sign or direction of current of work circuits on the incidence of a selected threshold of light on the photoelectric element.

40. The matter of claim 32 having a grid element in the primary Work circuit, electrically identical with the grid element of the secondary work circuit.

41. The matter of claim 32 when provided with a primary work circuit cathode-heating circuit adapted to heat the said cathode on being energized, and means to energize said heating circuit, and having a grid element in the primary work circuit electrically identical with the grid element of the secondary work circuit.

42. The matter of claim' 32 when the photoelectric element is provided with a heating circuit, independent of said work circuits, said circuit adapted to supply electrons to said Photoelectric element upon the withdrawal of electrons therefrom consequent upon the incidence of light rays on said photoelectric element, and having a grid element in the primary work circuit electrically identical with the grid element of the secondary work circuit.

43. The matter of claim 32 when provided with a primary work circuit cathode-heating circuit adapted to heat the said cathode on being energized and means to energize said heating circuit, and when the photoelectric element is provided with a heating circuit, independent of said work circuits, said circuit adapted to supply electrons to said photoelectric element upon the withdrawal of electrons therefrom consequent upon the incidence of light rays on said photoelectric element, and having a grid element in the primary work circuit electrically identical with the grid element of the secondary work circuit.

44. The matter of claim 32 when said grid circuit is provided with critical biasing means adapted to change sign or direction of current of work circuits on the incidence of a selected threshold of light on the photoelectric element and having a grid element in the primary work circuit electrically identical with the grid element of the secondary work circuit.

45. The matter of claim 32 when provided with a primary work circuit cathode-heating circuit adapted to heat the said cathode on being energized, and means to energize said heating circuit, when said grid circuit is provided with critical biasing means adapted to change sign or direction of current of work circuits on the incidence of a selected threshold of light on the photoelectric element, and having a grid element in the primary work circuit electrically identical with the grid element of the secondary work circuit.

46. The matter of claim 32 when the photoelectric element is provided with a heating circuit, independent of said work circuits, said cir-I cuit adapted to supply electrons to said photoelectric element upon the withdrawal of electrons therefrom consequent upon the incidence of light rays on said photoelectric elements, and when said grid circuit is provided with critical biasing means adapted to change sign or direction of current of work circuits on the incidence of a selected threshold of light on the photoelectric element and having a grid element in the primary work circuit electrically identical with the grid element of the secondary work circuit.

47. The matter of claim 32 when provided with a primary work circuit cathode-heating circuit adapted to heat the said cathode on being energized and means to energize said heating circuit, and when the photoelectric element is provided with a heating circuit, independent of said work circuits, said circuit adapted to supply electrons to said photoelectric element on the withdrawal of electrons therefrom consequent upon the incidence of light rays on said photoelectric element, and when said grid circuit is provided with critical biasing means adapted to change sign or direction of current of work circuits on the incidence of a selected threshold of light on the photoelectric element, and having a grid element in the primary work circuit, electrically identical with the grid element of the secondary work circuit.

48. An organization of electrical elements and circuits comprising: a photoelectric cathode and an anode in a photoelectric cathode-to-anodc primary work circuit, with a space gap between said cathode and anode, a supplementary photoelectric element so positioned as to receive rays of light and adapted to effect, thereupon the conductivity of said gap, and an audion element, comprising a filament-cathode with heating circuit, an anode and a grid, with grid circuit, and a regenerative coupling between said grid circuit and said audion work circuit.

49. The matter oi.' claim 48 when said anodes are electrically integral.

50. The matter of claim 48 when -said photoelectric cathode is provided with means by which to be heated.

51. The matter of claim 48 when said supplementary photoelectric element is adapted to be heated, and is provided with means whereby to be heated.

52. The matter o1' 4claim 48 when said grid circuit is provided with critical biasing means, adapted to change sign or direction of current oi' said work circuit on the incidence of a selected threshold of light upon the photoelectric element.

53. The matter of claim 48 when said anodes are electrically integral and when said cathode is provided withmeans by which to be heated.

54. The matter oi.' claim 48 when said anodes are electrically integral, when said photoelectric cathode is provided with means by which to be heated, when said supplementary photoelectric element is adapted to be heated, and is provided with means whereby to be heated, and when said grid circuit is provided with critical biasing means, adapted to change sign or direction of current of said work circuit on the incidence of a selected threshold of light upon the photoelectric element.

55. An organization of electrical elements and circuits comprising in combination a photoelectric cell, with cathode photoelectrically active, an anode and a space gap therebetween, an audion system with electrically heated cathode, anode and space gap therebetween. and a grid in said space gap, with a grid circuit. said photo- 10 said grid circuit and said identical anodes.

i 58. The matter of claim 55 including a supplementary photoelectric element positioned in the cathode-to-anode gap o! the photoelectric cell and sn independent circuit therefor adapted to heat said supplementary photoelectric element.

57. The mattei' of claim 55 when the photoelectric cathode is provided with heating means.

5.8. The matter of claim 55 and critical biasing means adapted to change sign or direction oi work current on the incidence ot a selected threshold o! iight incident upon the photoelectric 10 

